alcium
chloride, the barium chloride being extracted from the fused mass by water,
leaving a residue of insoluble calcium sulphide. The chloride crystallizes
in colourless rhombic tables of specific gravity 3.0 and is readily soluble
in water, but is almost insoluble in concentrated hydrochloric acid and in
absolute alcohol. It can be obtained in the anhydrous condition by heating
it gently to about 120deg C. It has a bitter taste and is a strong poison.
Barium bromide is prepared by saturating baryta-water or by decomposing
barium carbonate with hydrobromic acid. It crystallizes as BaBr_2 . 2H_2O
isomorphous with barium chloride. Barium bromate, Ba(BrO_3)_2, can be
prepared by the action of excess of bromine on baryta-water, or by
decomposing a boiling aqueous solution of 100 parts of potassium bromate
with a similar solution of 74 parts of crystallized barium chloride. It
crystallizes in the monoclinic system, and separates from its aqueous
solution as Ba(BrO_3)_2 . H_2O. On heating, it begins to decompose at
260-265deg C. Barium chlorate, Ba(ClO_3)_2, is obtained by adding barium
chloride to sodium chlorate solution; on concentration of the solution
sodium chloride separates first, and then on further evaporation barium
chlorate crystallizes out and can be purified by recrystallization. It can
also be obtained by suspending barium carbonate in boiling water and
passing in chlorine. It crystallizes in monoclinic prisms of composition
Ba(ClO_3)_2 . H_2O, and begins to decompose on being heated to 250deg C.
Barium iodate, Ba(IO_3)_2, is obtained by the action of excess of iodic
acid on hot caustic baryta solution or by adding sodium iodate to barium
chloride solution. It crystallizes in monoclinic prisms of composition
Ba(IO_3)_2 . H_2O, and is only very sparingly soluble in cold water.

Barium carbide, BaC_2, is prepared by a method similar to that in use for
the preparation of calcium carbide (see ACETYLENE). L. Maquenne has also
obtained it by distilling a mixture of barium amalgam and carbon in a
stream of hydrogen. Barium sulphide, BaS, is obtained by passing
sulphuretted hydrogen over heated barium monoxide, or better by fusion of
the sulphate with a small coal. It is a white powder which is readily
decomposed by water with the formation of the hydroxide and hydrosulphide.
The phosphorescence of the sulphide obtained by heating the thiosulphate is
much increased by adding uranium, bismuth, or thorium before ignition